WIP: Use lua-cqueues to watch RPZ file and reload on change.

Not sure if there's a better place to put get_dir_and_file() function? It's needed to separate the directory and file from the path because lua-cqueues requires watching the directory that contains the file(s) you're interested in.

This will also create a new notify instance for every call to policy.rpz(), not entirely sure of the overhead of this or if people reasonably will call policy.rpz() multiple times. I looked at doing some tracking but it didn't seem work the massive effort (the way I see it it would require converting to a class to store/track the instances).

Lastly, while Windows is neither supported nor planned to be supported, putting a requirement on lua-cqueues will break any work on Windows since it isn't compatible.